You can probably hear the motorbike they use to run the lure. Some clever cookie has mounted a motorbike on a stand and replaced the back tyre with a pulley. The pulley drags the lure around the course and you adjust the speed by “riding” the motorbike.
Other clubs use an electric one, but they tend to overheat too quickly and run out of battery before the day is done. Its a fair load dragging a bit of rope around a ~500M loop via a heap of pulleys in the ground. The noise of the motorbike also gets the puppies more excited than the quiet “zzz zzz” of the electric one.
Or as they call it in France, Le Porn